bloc_test 2.1.0

A testing library which makes it easy to test blocs. Built to be used with the bloc state management package.

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A Dart package that makes testing blocs easy. Built to work with bloc and mockito.

Create a Mock Bloc

import 'package:bloc_test/bloc_test.dart';

class MockCounterBloc extends MockBloc<CounterEvent, int> implements CounterBloc {}

Stub the Bloc Stream

whenListen creates a stub response for the listen method on a Bloc. Use whenListen if you want to return a canned Stream of states for a bloc instance.

// Create a mock instance
final counterBloc = MockCounterBloc();

// Stub the bloc `Stream`
whenListen(counterBloc, Stream.fromIterable([0, 1, 2, 3]));

// Assert that the bloc emits the stubbed `Stream`.
expectLater(counterBloc, emitsInOrder(<int>[0, 1, 2, 3])))

Unit Test a Real Bloc with blocTest

blocTest creates a new bloc-specific test case with the given description. blocTest will handle asserting that the bloc emits the expected states (in order) after act is executed. blocTest also handles ensuring that no additional states are emitted by closing the bloc stream before evaluating the expectation.

build should be used for all bloc initialization and preparation and must return the bloc under test.

act is an optional callback which will be invoked with the bloc under test and should be used to add events to the bloc.

expect is an Iterable<State> which the bloc under test is expected to emit after act is executed.

group('CounterBloc', () {
    blocTest(
      'emits [0] when nothing is added',
      build: () => CounterBloc(),
      expect: [0],
    );

    blocTest(
      'emits [0, 1] when CounterEvent.increment is added',
      build: () => CounterBloc(),
      act: (bloc) => bloc.add(CounterEvent.increment),
      expect: [0, 1],
    );
});

Assert with Confidence using emitsExactly

emitsExactly is similar to emitsInOrder but asserts that the provided bloc emits only the expected states in the exact order in which they were provided.

group('CounterBloc', () {
    test('emits [0] when nothing is added', () async {
      final bloc = CounterBloc();
      await emitsExactly(bloc, [0]);
    });

    test('emits [0, 1] when CounterEvent.increment is added', () async {
      final bloc = CounterBloc();
      bloc.add(CounterEvent.increment);
      await emitsExactly(bloc, [0, 1]);
    });
});

Dart Versions

• Dart 2: >= 2.0.0

Maintainers

• Felix Angelov